Spectral,thermal, biological and multi‐heating rate kinetic properties of Cu(II) complexes containing N2O2 donor ligands: 1,10‐phenanthroline and acyl coumarins

A series of newly synthesized coumarin‐based mixed‐ligand copper complexes with 1,10‐phenanthroline (Ph) were investigated by means of thermogravimetry, differential thermogravimetry, differential scanning calorimetry (DSC), electronic spectra and magnetic measurements. Structural and spectroscopic properties of neutral bidentate ligands as well as all complexes were studied on the basis of mass spectra, NMR (¹H and ¹³C) spectra, FT‐IR spectrophotometry and elemental analyses. IR spectral data suggest tetra‐coordinated N₂O₂ bonding of ligand toward metal ion. Dynamic scan of DSC experiments for copper complexes were obtained at different heating rates (2.5–20°C min^?1). Isoconversion methods of Kissinger and Ozawa were used for the determination of the pre‐exponential factor (A), activation energy (E_a) and order of reaction (n). Kinetic parameters for second‐step degradation obtained by Kissinger's and Ozawa's methods are in good agreement. The results indicate that complexes are much stronger free radical scavenger and antioxidant compounds than ligands. Antimycobacterial screening of ligand and its copper compound against Mycobacterium tuberculosis shows clear enhancement in antitubercular activity upon copper complexation. Also good antimicrobial activities of the complexes against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhus, Aspergillus niger, Candida albicans and Aspergillus clavatus have been found compared to its free ligands. Copyright © 2012 John Wiley & Sons, Ltd.